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Exam 8: Introduction to Hypothesis Testing.

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Question 21

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If all other factors are held constant,increasing the sample size from n = 25 to n = 100 will increase the power of a statistical test.

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Question 22

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A hypothesis test involves a comparison of which two elements?

A) Research results from a sample and a hypothesis about a population
B) Research results from a population and a hypothesis about a sample
C) Research results from a population and a hypothesis about the population
D) Research results from a sample and a hypothesis about the sample

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Question 23

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By selecting a larger alpha level,a researcher is ______.

Which of the following correctly describes the effect of increasing the alpha level (for example,from .01 to .05) ?

It is possible for a very small treatment effect to be a statistically significant treatment effect.

There is always a possibility that the decision reached in a hypothesis test is incorrect.

The critical boundaries for a hypothesis test are z = +1.96 and -1.96.If the z-score for the sample data is z = -1.90,what is the correct statistical decision?

A researcher administers a treatment to a sample from a population with a mean of µ = 60.If the treatment is expected to increase scores and a one-tailed test is used to evaluate the treatment effect,then the null hypothesis would state that µ ≥ 60.

If other factors are held constant,lowering the alpha level will increase the power of a hypothesis test.

A researcher administers a treatment to a sample of n = 16 selected from a population with µ = 40 and Ϭ = 8.If the sample mean after treatment is M = 42,then Cohen's d = 1.00.

Some researchers claim that herbal supplements such as ginseng or ginkgo biloba enhance human memory.To test this claim,a researcher selects a sample of n = 25 college students.Each student is given a ginkgo biloba supplement daily for six weeks and then all the participants are given a standardized memory test.For the population,scores on the test are normally distributed with μ = 70 and σ = 15.The sample of n = 25 students had a mean score of M = 75. a.Are the data sufficient to say that the herb has a significant effect on memory? Use a two-tailed test with α = .05. b.Compute Cohen's d for this study.

What is the consequence of a Type II error?

If a hypothesis test produces a z-score in the critical region,what decision should be made?

Under what circumstances can a very small treatment effect still be significant?

What is the relationship between the alpha level,the size of the critical region,and the risk of a Type I error?

What is measured by the denominator of the z-score test statistic?

What is measured by the numerator of the z-score test statistic?

A researcher would like to determine whether an over-the-counter cold medication has an effect on mental alertness.A sample of n = 16 participants is obtained,and each person is given a standard dose of the medication one hour before being tested in a driving simulation task.For the general population,scores on the simulation task are normally distributed with μ = 60 and σ = 8.The individuals in the sample had an average score of M = 56.5. a.Can the researcher conclude that scores on the driving simulation task are significantly different after taking the medication? Use a two-tailed test with α = .05. b.Can the researcher conclude that scores on the driving simulation task are significantly lower after taking the medication? Use a one-tailed test with α = .05. c.Compute Cohen's d to measure the size of the effect.

The alpha level determines the risk of a Type I error.

A researcher is evaluating a treatment that is expected to increase scores.If a one-tailed test with α = .05 is used,then the critical region consists of z-scores less than -1.65.